An electric generator which can be used as a dynamo in an internal combustion engine usually comprises a radially outer stator, a radially inner rotor and a housing on which the rotor is arranged so as to be rotatable about a rotatable axis, on which the stator is arranged in a rotationally fixed fashion and which has a housing casing which runs around in the circumferential direction, a front side wall and a rear side wall. During the operation of the generator, the conversion of mechanical work into electrical energy also generates heat which has to be carried away from the generator in order to be able to meet the specifications for the durability of the generator. For this purpose, the generator can be equipped with an axially outer impeller wheel which is arranged on an outer side facing axially away from the rear side wall, of the front side wall in a rotationally fixed fashion on the rotor. In order then to be able to bring about a throughflow through the generator in order to be able to take up and carry away heat during the operation of the generator, a primary air inlet can also be provided, said primary air inlet having a plurality of, preferably axial, primary inlet openings which are formed in the rear side wall. Furthermore, an air outlet can be provided which has a plurality of, preferably axial, outlet openings formed in the front side wall. As a result, a primary air path is formed which leads inside the housing from the primary air inlet to the air outlet. During the operation of the generator, the impeller wheel rotates with the rotor and in doing so generates a partial vacuum at the outer side of the front side wall, in the region of the outlet openings. This partial vacuum then itself generates a primary air flow which enters the housing through the primary air inlet, follows the primary air path in the interior of the housing, and exits again from the housing through the air outlet. The primary air flow expediently flows around the rotor along the primary air path, as a result of which heat can be intensively carried away from the rotor.
Increasing power demands for the generator can give rise to increased generation of heat, with the result that solutions are sought for carrying away the heat better from the generator. Higher power demands can, however, also lead to a situation in which, apart from the rotor, the components of the generator are also subjected to higher temperatures, which affects the service life of the generator. For example, a front rotor bearing can also be subjected to high thermal loading. The front rotor bearing is located in the front side wall. The stator or a stator winding can also be subjected to increased thermal loading.